New S4 Avant - A couple of questions...

[cmdrew]

Hi,

Just picked up a 2003 S4 Avant and driven it 200 miles back from London. The car is great, loads of power and on a slow journey back from London I got 30MPG from it which I was astounded at. Admittedly the M1 was clogged up badly and I rarely got over 70MPH but still good I thought.

However a couple of things I have now noticed that I wondered if anyone can help with. The climate control does not seem to have the air con working. I have put both sides on Auto but the Econ button is lit. Pressing the button causes the light to go out and then immediately come back on again. The engine has been out for a clutch / top end rebuild and I wonder if they just didn't regass the air con and maybe the Audi is clever enough to know the air con doesn't work so won't switch of econ mode???

Secondly the rear parking sensors don't seem to be working properly. Sometimes I get a single beep and then they seem to work, other times I don't get anything not even the initial beep when it goes into reverse and other times I get a constant beep. Is there a way to diagnose the problem?

Thanks

 

[cnut]

The air con problem is probably the G65 sensor, see here: http://www.audi-sport.net/vb/a4-a4-...sis/156871-aircon-not-working-g65-sensor.html

Probably best to get the car hooked up on VCDS to check the parking sensor fault.

 

[dualmono21]

air con could be the front sensor ... check it with vcds
it could also be the compressor which is directly driven off the timing chain ...if its seized the clutch will not engage
however there is also another problem with these as in they are directly driven off the timing chain and are prone for either wearing the gearing or or the spline drive where it fits
they only way youll find out is getting under the front passenger side of the car and look up above the front engine mount you should see a small 6" long tube about 1/2" in diameter which spins with engine speed ...
if its not spinning the air con will never work as the compressor isnt driving if it is spinning the compressor could be seized or it could be the air con sensor

 

[dualmono21]

rear parking sensors has a control unit in the back of the passenger side compartment in the boot
check the condition and then check the sensors themselves ...has the bumper been resprayed ???

 

[Az]

Doesn't the econ light stay on if the gas has run out as well? My wife's is constantly on at the moment too, but its only recently stayed on, so I'm hoping it just needs re-gassing.

To OP, with the rear parking sensors put the ignition on (but don't start the engine) put it in reverse and then put your ear right up to each parking sensor, you should hear the parking sensors ticking, this suggests that they are working properly, if you don't hear any of them ticking then it suggests a dead sensor which needs replacing. If none of them are ticking then that'll more than likely point towards the control module in the boot.

If just one of the sensors is knackered it'll throw all of them out which normally makes the long bleep when you put it in reverse.

 

[cmdrew]

WRT the parking sensors it looks as if one of the sensors is not working. I tried the 'listen for each one clicking' test and one isn't so I guess first step is to replace that one. The interesting thing about the air con fault is that the econ light won't go out but reading the suggested threads it seems as this is normal if there is a fault in the system. Looks like I need a code reader that can get fault codes from the air con system.

 

[Az]

WRT the parking sensors it looks as if one of the sensors is not working. I tried the 'listen for each one clicking' test and one isn't so I guess first step is to replace that one. The interesting thing about the air con fault is that the econ light won't go out but reading the suggested threads it seems as this is normal if there is a fault in the system. Looks like I need a code reader that can get fault codes from the air con system.

I had vcds plugged into my wife's avant and that showed no fault codes for her aircon even though the econ like is constantly on, so I'm not sure if vcds will always pick up a fault with it, but, it should do if its a sensor problem, that's why I'm hoping its just the fact that it needs re-gassing.

 

[dualmono21]

the air conditioning wont allways have a fault code but it will have a pressure reading in the measuring blocks section
the only other fault i can think of is a hvac failure

 

[cmdrew]

the air conditioning wont allways have a fault code but it will have a pressure reading in the measuring blocks section
the only other fault i can think of is a hvac failure

Just had it down to Kwik-fit who have re-gassed the system as it was completely empty and it seems to be working. No leak was detected but we will see...

 

[Az]

Just had it down to Kwik-fit who have re-gassed the system as it was completely empty and it seems to be working. No leak was detected but we will see...

Econ light now goes out?

 

[cmdrew]

Ok now I am confused. All gassed up and the econ light will go out but the air con still doesn't work. The climate control tries to cool the car down by putting the dan to max but it seems as if the air coming out of the vents is hotter than ambient. I also don't hear the compressor cut in as I would expect to. Checked the fuses and they are ok. Any suggestions as to what to look for next. I have confirmed that the system still has pressure.

 

[dualmono21]

see my earlier post
check first to see the compressor itself is actually being driven ... if you cannot see the shaft turning then it may well have been removed as it wears prematurely
the system will appear normal and have no fault codes , but the compressor itself will not be turning hence warm air

 

[cmdrew]

I'm going to get a VAG COM cable so that I can check for air con fault codes (and others!) as the econ light can sometimes be switched off but sometimes not. One quick follow up though - should the engine fan (auxillary) be running when the air con is on (econ light off) as other cars I have had the fan runs constantly at a low speed with air con on but on the audi it isn't and doesn't seem to ever run.